The 14-year-old, from Tydd St Giles, failed to retain his Super Karts USA SuperNationals title in controversial circumstances.

Determined to sign off his glittering junior career in style, Russell dominated the early proceedings by winning all three heats.

He looked in control of the grand final but, as the race settled down, rival Lance Stroll seized the lead and pulled away to take a shock win.

Second-placed Russell was ready to be hailed as vice-champion but as he took the chequered flag it emerged that the stewards had disqualified Stroll. The Canadian had an irregularity with his exhaust header, which delivered more power to the engine and gave him a speed advantage.